Axial fans which are disposed between a radiator and a combustion engine of a motor vehicle are known from the prior art. Axial fans of said kind are assigned air guide vanes which cover the entire area of the outlet cross-section and serve to redirect the rotational energy of the streaming air in an axial direction in order thereby to intensify the axial air flow.
Axial-radial fans are becoming increasingly important owing to the fact that less and less space is available to allow a clearance between the combustion engine and the fan module due to changed installation conditions in the engine compartments of modern motor vehicles. FIGS. 14 and 15 show schematics of a fan module 400 disposed between a radiator 200 and combustion engine 300 of a motor vehicle and having a fan motor 500, FIG. 11 showing an axial air flow 600 and FIG. 12 an axial-radial air flow 700. With designs of said type, the air stream enters the fan axially and exits the latter again partially radially. In this arrangement, however, the use of known air guide vanes leads to a reduction in the performance of the fans, since radial air flows are disrupted due to the deflecting of the air in the axial direction by the air guide vanes.
Furthermore the operating temperature of the fan motor is increased due to the constricted layout, which necessitates more effective cooling of the fan motor as well as in particular the integrated electronics. At the same time more and more powerful fan motors are being used, so the cooling requirement of the fan motor is also steadily increasing. Finally, higher ambient and operating temperatures for the fan motors must also increasingly be assumed due to the more and more powerful combustion engines.
EP 0387987 A2 describes a support ring for receiving a cooling fan motor in a housing, wherein an inner support ring is positioned centrally in a circular opening with the aid of radial support vanes. The radial support vanes are assigned additional stabilizing rings which serve on the one hand to increase the mechanical stability of the mounting apparatus and on the other hand to redirect the cooling airflow from a radial to an axial direction and thus increase the fan's efficiency.
US 2005/0186070 A1 shows a fan assembly in which the air inlet opening is covered by air guide elements, the number of air guide elements in a first area in the center of the opening being different from the number of air guide elements in a second area at the circumference of the opening. In this arrangement the number of air guide elements is chosen in accordance with possibly occurring pressure differences across the length of the fan blades in such a way that the fan performance is optimized.